JPS59186445A - Bus receiver with equalizing function - Google Patents

Abstract

PURPOSE:To increase a communication line in speed and distance by providing the bus receiver of every station with a proper waveform equalizing function. CONSTITUTION:In a figure, 1 is a coupler fitted to a transmission line DB, and 2 is a driver for transmission; and 3 is an amplifier for reception, and 4 is a discriminator which receives the output of an amplifier. The amplifier 3 and discriminator 4 constitute a bus receiver and the amplifier 3 is provided with the equalizing function. The figure shows an electric circuit diagram showing one constitution of the receiving amplifier which has the equalizing function. The amplifier shown in the figure is composed of the differential amplifier using transistors (TR) Q1 and Q2 and an RC series circuit connected between the emitters of the TRs Q1 and Q2 constitutes an equalizing circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a data way path receiver, and more particularly to a path receiver that is provided with an equalization function to increase the speed and distance of a communication line.

A so-called data way, in which a single transmission line (often a coaxial cable) is shared by multiple devices, is widely used, and an example of its configuration is shown in FIG. The figure shows a linear dataway. In the figure, 81 to 5n (n is an integer, the same applies hereinafter) are stations, T1 to Tn are transceivers, and A1 to
An is a coupler, DB is a transmission line, and each stage is 81 to S11! : Transmission line DB is path coupler A1-A
n and converted to logic levels by transceivers T1-Tn. In dataways configured in this way, limitations on transmission length and number of stations are limited by attenuation,
Determined by band and reflection. That is, as the number of loads (stations) increases, attenuation increases and reflections increase due to insertion. 1. As cable length increases, attenuation and bandwidth limiting increase.

FIG. 2 is a diagram showing the signal propagation characteristics. In the figure,
(a) of station S1, (b) of stage S
2, (C) shows the respective received signal waveforms of station Sn. It can be seen that at stage S, the received signal is attenuated and its waveform becomes flat.
However, as the length of the cable increases, attenuation and bandwidth limitations increase, and in the case of dataways, the transmission path changes for each communication, so equalization is not generally performed. For this reason,
Compared to the case of one-to-one transmission, the transmission length of the linear dataway shown in Fig. 1 is significantly limited1.The present invention has been made in view of these points.
The present invention realizes a path receiver that is equipped with an appropriate waveform equalization function for each station, thereby increasing the speed and distance of communication lines.

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 3 is a diagram showing the configuration of the transceiver.

In the figure, 1 is a coupler attached to the transmission line DB;
2 is a transmitting driver, 6 is a receiving amplifier, and 4 is a discriminator that receives the output of the amplifier. The amplifier 3 and the discriminator 4 constitute a path receiver, and the amplifier 3 is provided with an equalization function. FIG. 4 is a diagram showing signal transfer characteristics. The horizontal axis is frequency and the vertical axis is gain. f is station S2
(See Figure 1) 1 and fB2 indicate the characteristics of station Sn, where 1 indicates no equalization, 2 indicates appropriate equalization, and 5 indicates unsuitable equalization. . FIG. 5 is a diagram showing transmission waveforms, (a) of station S;
(b) shows the transmission waveform of stage S2. Numbers 1 to 5 in the figure are the same as those in FIG. 1 is the case without equalization, which is appropriate for nearby stations but inappropriate for distant stations. 5 is possible if equalization is performed so that a complete waveform can be obtained at stage S, but if this is done, the equalization will be too large at stage S2. On the other hand, in 2, station Sn
In this case, the equalization is insufficient, but on the other hand, the waveform does not deteriorate much even in the system S2.

From this, if the amplifier 3 (Fig. 5) is equipped with an equalization function that sets the equalization amount so that the underequalization amount at station S and the overequalization amount at station S2 are equal, the signal will not be attenuated. This will make it possible to realize a data way.

FIG. 6 is an electrical circuit diagram showing one configuration of a receiving amplifier having an equalization function. The amplifier shown in the figure is composed of a differential amplifier using transistors Q□ and Q2.
RC connected between the emitter of transistor Q and Q2
The series circuit 10 constitutes an equalization circuit. If the collector resistance value is RL and the emitter resistance value is RE, then the gain G of this amplifier is given by the following equation.

ω: Angular frequency TloR+ 2RE T2'''CR Now, assuming that the transfer characteristic from station S1 to stage sn sn is G and the transfer characteristic to station s2 is 02, these are given by the following equations.

n 1+jωTi
(2) G2''1 (3) KL, T9.: When the constant Gn''2 is equalized to equation (1), it becomes as follows.

1+%T1(5) G21=G2°G′″Ko 1+j (support) T2 where,
When selecting Ti=T□, Gn is equalized to Qnl (see the formula below).

G1=9. ni□(6) 01+JωT2 G2! =Ko Kansu (7) Here, the 7th
Consider making the waveform deviation Δ at station S2 equal to the waveform deviation Δ at station S, as shown in FIGS.

The condition that both are equal is T9. = 2T2do) At this time,
Equation (6) is given by the following equation.

a l = 1! , −to−tr(n) n01+jωdαη From the equation, a band twice as large as the band expressed by equation (2) can be obtained. That is, the transmission distance can be extended or the transmission speed can be doubled with an extremely simple configuration. FIG. 7(,) shows the received waveform of the stacylons S2 and Sn when they are not equalized, and FIG. 7(b) shows the received waveform after equalization. In each case, 1 indicates the waveform of S2, and 2 indicates the waveform of Sn.

As described in detail above, according to the present invention, it is possible to realize a path receiver that can increase the speed and distance of a communication line by providing a suitable waveform equalization function to the path receiver of each station. I can do it.

[Brief explanation of the drawing]

Fig. 1 shows the configuration of the dataway, Fig. 2 shows the signal propagation characteristics, Fig. 5 shows the transceiver configuration, Fig. 4 shows the signal transfer characteristics, Fig. 5 6 is a diagram showing a transmission waveform, FIG. 6 is an electric circuit diagram showing an example of a specific configuration of an amplifier for receiving, and FIG. 7 is a diagram showing waveform deviation. S1-Sn...Station, T1-Tn...Transceiver, A1-An...Coupler, DB...Transmission line, 1...Coupler, 2 Driver, 3...Amplifier, 4...
... Discriminator, 10... Equalization circuit, Ql, G2... Transistor. Figure 1 Figure 2 Figure 3 Figure 4 (J Figure 5 Figure 6 Figure CC Figure 7

Claims (2)

[Claims] (1) A pass receiver installed in the four-input part of each stage in a data unit system to which multiple stations are connected, and attenuation in the high frequency region of the gain when multiple stages g/ are connected. A path receiver with an equalization function, characterized in that an amplifier having an equalization characteristic for compensating the characteristics is provided inside the receiver. (2) When the transmission characteristic G of the communication line is expressed by G = x: i n 1 + j ω T ω: angular wave number KL, TL: constant, it is characterized by having an equalization characteristic expressed as the equalization characteristic G. Claim 1:
Pass receiver with equalization function as described in section.